Patients with early Parkinson’s disease who respond to drug therapy gain improvement in their symptoms and quality of life when they receive deep-brain stimulation from an implanted medical device, a study showed.
Brain stimulation is now reserved for advanced Parkinson’s patients with severe complications and inconsistent response to drug treatment. The findings suggest patients at an earlier stage of the disease may do even better, reaping benefits before the progressive neurological illness has eroded their physical function, social activity and professional lives.
The researchers tracked 251 patients with Parkinson’s for an average of 7.5 years after they were treated with drug therapy, or drugs plus deep-brain stimulation with Medtronic Inc.’s Kinetra or Soletra devices. Quality of life improved significantly for those getting both treatments, while it worsened slightly for those given only drugs, according to the study published yesterday in the New England Journal of Medicine.
“The observed difference between the treatment groups is thus due to an improvement among patients receiving neurostimulation,” said the researchers led by Michael Schuepbach, from the University of Pierre and Marie Curie and Inserm in Paris. “As a main benefit from the patient’s perspective, activities of daily living were improved among patients with neurostimulation in the worst condition during the day.”
Patients receiving brain stimulation also had a significantly greater improvement in being able to take care of themselves, their emotional well-being and cognition than reported in previous studies involving more severe patients, the researchers said. The stimulation didn’t improve mobility and was linked to additional side effects, including suicide.
About 1.5 million people in the U.S. have Parkinson’s, according to the Parkinson’s Disease Foundation. The number is expected to double by 2030 because of the aging population, Caroline Tanner, from Stanford University School of Medicine’s department of health research and policy, and the Parkinson’s Institute in Sunnyvale, California, wrote in an editorial accompanying the study.
People with the neurological disease gradually lose neurons that make the brain chemical dopamine. The lack of dopamine leads to increasing activity in a part of the brain called the subthalamic nucleus, which influences movement.
Early-stage Parkinson’s patients now are treated with drugs designed to increase dopamine in the brain. They typically lose their benefits after several years and trigger serious side effects. That is when deep-brain stimulation is employed to shoot an electrical current into the subthalamic area of the brain and block the signals that cause symptoms of the disease.
The patients in the study were 60 years old or younger, in good health and still responding to drug treatment, a relatively small subset of those with Parkinson’s disease, Tanner wrote. It’s not clear if similar benefits will emerge in older, more conventional patients who often have other ailments, she said.
The stimulation doesn’t stop the progression of the disease itself and improves only some of the motor symptoms, she said.
“Ideally, treatment of Parkinson’s disease should improve not only motor, but all features of the disease,” Tanner said. “Neurostimulation of the subthalamic nucleus does not ameliorate all symptoms of Parkinson’s disease, but for carefully chosen, highly functioning patients, it may provide many additional years of good functioning.”
Medtronic, based in Minneapolis, is the only company with a brain stimulation device approved to treat Parkinson’s disease. St. Jude Medical Inc., based in St. Paul, Minnesota, and Boston Scientific Corp. from Natick, Massachusetts, sell similar devices in Europe and are pursuing U.S. Food and Drug Administration approval.
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